1. Field of the Invention
The present invention relates to an ink jet recording apparatus which forms an image on the recording medium by discharging the ink.
2. Related Background Art
Conventionally, various recording methods have been put to practical use for the image forming apparatus (so-called a recording apparatus or a printer) for forming an image on the recording medium such as a paper and OHP recording sheet.
The recording methods include a wire dot method which is an impact recording method, a thermal transfer method using an ink ribbon of transferring the ink fused by heating, a thermal recording method using a thermosensitive recording paper which is colored upon the reaction with the heating of a recording head, and an ink jet recording method of forming an image on the recording medium by discharging the ink.
Among a variety of kinds of recording methods, attention is particularly paid to the ink jet recording method as a silent method with low running costs because of discharging the ink directly onto the recording medium.
In the ink jet recording apparatuses with such an ink jet recording method, the type of using a disposable recording head is typically utilized in practice in which the recording head for discharging the ink and an ink reservoir (ink tank) for reserving the ink are integrated and mounted exchangeably on the recording apparatus. Also, an ink jet recording apparatus of the type in which only an ink reservoir apart from a recording head is exchanged with the recording head as permanent or longer life type has been put to practical use because of its inexpensive costs for the recording head.
In the above ink jet recording apparatuses, capping means for protecting the ink from drying by covering the ink discharge ports (nozzles) of the recording head is provided or a discharge recovery processing of discharging the ink through the nozzles to remove the ink having the increased viscosity or the ink containing the dust or dirt therein is typically practiced, in order to maintain the ink discharge condition of the recording head excellent and normal.
Exemplary of the above capping means is a cap formed of an elastic material such as rubber which is placed opposite to the nozzle formation face of the recording head, which cap is able to be brought into or out of contact with the nozzle formation face at a position for capping, thereby preventing the drying of the ink in or near the nozzles by capping, when the discharging of the ink is not performed beyond a predetermined time in other than the recording operation or even during the recording operation.
Further, exemplary of the above discharge recovery processing is a processing (preliminary discharge) of discharging the ink through all the discharge ports by driving the energy generating elements for use in discharging the ink, which are provided within the nozzles of the recording head, thereby removing air bubbles or the dust and dirt or the viscosity-increased ink unsuitable for the recording, as the discharge failure factors, by providing a cap which can be brought into or out of contact with the nozzle formation face of the recording head, with said cap opposed to the nozzle formation face of the recording head, or otherwise a processing (suction recovery processing) of compulsorily discharging the ink through all the discharge ports using a suction pump, with the discharge formation face covered with the cap, thereby removing the ink as the discharge failure factors.
Where the recording head and the ink tank integrated is exchangeably mounted on the recording apparatus or where the ink tank is exchangeably mounted, there often occur such instances where a newly mounted recording head may be in unexcellent recording condition. This may be caused by the vibrations during the transport or the penetration of air bubbles in the nozzles of the recording head or the ink supply passage into the nozzles, which may disrupt the ink supply so that the ink is not properly filled in the nozzles or the ink flow passages. Also, in the constitution where the replaceable ink tank is used, the excellent recording condition in mounting a new ink tank may not be attained, because the air may enter into a fitting portion between the ink tank and the ink supply passage into the nozzles. If the recording operation is performed while the ink is improperly filled, the energy generating elements for use in discharging the ink will generate the discharge energy, without ink, so that the energy generating elements may be broken. Also, in the ink jet systems of the type of discharging the ink by the use of a pressure caused by the state change due to the heat of the ink, using the heat energy as the discharge energy, the heat energy generating elements may generate heat without ink, often resulting in the breakage of the heat energy generating elements. In order to avoid such failures, the mechanisms have been recently developed in which, for example, the operator of the recording apparatus is prompted to perform the discharge recovery operation upon replacing the recording head, or the replacement of the recording head is automatically sensed to thereby carry out the discharge recovery processing prior to the recording operation.
Also, the capping means is often provided with a suction pump for effecting the discharge recovery processing, in which the discharge recovery processing is performed by activating the suction pump to discharge the ink, with the nozzle formation face covered with a cap. Further, of the discharge recovery processing, the art of effecting preliminary discharge toward the cap and receiving the waste ink discharged with the preliminary discharge within the cap is commonly practiced, owing to the reasons that there is no necessity of waste ink receiving member and the waste ink received is easily processed.
Where there remains the ink discharged by the above processing within the cap, the ink unsuitable for the recording may make contact with the nozzles of the recording head, bringing about some nonconformity in the subsequent recording operations, when the suction pump is activated for the capping operation or the discharge recovery processing. Further, when the cap is disposed vertically, there may occur such a nonconformity that the ink contaminates the recording apparatus or the recording sheet, because the ink within the cap drips. For the prevention of such nonconformities, to receive the ink within the cap into the ink receiving member (waste ink tank), it is the common practice to receive the ink within the cap into the waste ink tank in such a way as to operate the suction pump with the cap out of the recording head after the discharging of the ink from the recording head by means of the suction pump, or to calculate the predetermined number of preliminary discharges to be receivable within the cap from the amount of discharging the ink by one preliminary discharge and the amount of ink receivable within the cap, and upon the predetermined number of preliminary discharges being reached, to activate the suction pump with the cap out of the recording head.
FIG. 39 shows the constitution of a blade cleaner attached on a conventional carriage, as the blade cleaner for cleaning a wiper (wiper blade) in such a way as to wipe the discharge port face of the recording head.
49 is a blade cleaner unit, which is positioned with the embossed shape and secured to the carriage 11 by the snap-in action of a claw.
FIG. 30 is a chart representing the detailed configuration of the conventional blade cleaner unit 49.
49a is a blade cleaner, which is an absorbing member having high absorbing ability and less deformation, e.g., less swelling, after the absorption of the ink, wherein the ink adhering to the blade can be absorbed by this cleaner making contact with the blade. Specifically, Rubycerclean (Toyo Polymer Co., Ltd.), for example, can be used. 49b is a wiper cleaner holder for holding the wiper cleaner 49a. The wiper cleaner 49a is positioned by a boss portion provided in the wiper cleaner holder 49b, and screwed therein carried with a presser plate 49c. The presser plate 49c is of a shape to promote the drying of the wiper cleaner 49a, and to provide a number of opening portions to receive the ink splashed toward the wiper cleaner 49a, after a blade 59 wipes the face plane as shown in FIG. 42.
FIG. 41 shows the constitution of a conventional waste ink tank 55 having a breathable film.
A breathable film 55c is attached to the opening portion of the waste ink tank made of polypropylene. The breathable film 55c can pass therethrough the ink solvent vapor, but not the ink of liquid, and specifically, Vaporload (made by Teijin Limited), for example, is used.
A presser plate 55f is prepared for welding the breathable film, with the breathable film 55c carried therebetween.
FIG. 42 is a perspective view showing the appearance of a conventional recording apparatus.
As will be seen from this figure, conventionally, the waste ink tank 55 was disposed under a paper pan 37 adjacent to a head recovery unit containing a cap 51 and a pump 53. Also, with the conventional arrangement, not shown, it was requisite to arrange electrical components, owing to the space requirements, in the portion of an equipment containing a recording apparatus such as a word processor which is located under the head recovery unit and the waste ink tank, as well as its neighborhood.
FIG. 43 is a detailed exploded perspective view of a conventional waste ink seal 521 in part thereof.
The waste ink seal 521 which is a rubber member is a seal member for joining a pump shaft 519 which is the ink flow passage end portion of the pump 53 with an ink flow passage (not shown) extending in a vertical direction to an ink flow passage within the pump shaft 519. The pump shaft 519 is supported by a support plate 520, and rotated or swung in the directions as indicated by the arrow b around an axis a in the figure. A cylindrical bore fitted tightly around the pump shaft 519 is provided in the waste ink seal 521. Also, the outer shape of the waste ink seal 521 is substantially cylindrical and in coaxial with the above cylindrical bore. A waste ink cap 523 is provided with a bore which is of a shape identical to, and somewhat smaller in size than, the outer shape of the waste ink seal 521, within which the waste ink seal 521 is fitted.
Also, the printers of the ink jet system have conventionally a mechanism (cap means) for protecting the nozzles, when not printing, to prevent the clogging of the ink discharge nozzles due to the drying. And the on position of a carriage home sensor for detecting the position of a carriage having a head cartridge mounted therein, and the capping position at which the nozzle protection mechanism is activated, are mechanically set in predetermined dimensions, and assembled. Thus, the number of driving steps (constant value) of the carriage motor corresponding to the dimensions is prewritten into the ROM, and the capping position (i.e., carriage home position) is determined by driving a predetermined step number stored in the ROM from the on position of the carriage home sensor, irrespective of the conditions such as printer temperature, when the capping is made.
Also, when stopped at the carriage home position, the carriage is stopped in a stable phase (i.e., a phase where it is stably stopped when not excited) closest to the excitation phase of carriage motor at the carriage home position calculated from the on position of the carriage home sensor and the step number written in the ROM. And when the carriage is redriven, the driving is started from the excitation phase calculated previously.
However, in the above conventional example, the following problems were encountered.
At first, in carrying out the discharge recovery processing upon replacing the recording head or the ink tank, the demand for the operator of the recording apparatus to perform that processing is troublesome to the operation, and it is difficult to know whether the discharge recovery processing is securely performed by the operator.
In the constitution wherein the replacement of the recording head or ink tank is automatically sensed to effect the discharge recovery processing prior to the recording operation, there is a problem that when the discharge recovery processing, based on an instruction from the operator of the recording apparatus immediately after the replacement of the recording head or ink tank, is performed, a further discharge recovery processing based on sensing the replacement will be performed, resulting in the wasteful ink discharge from the recording head. The wasteful ink discharge led to the problem that in addition to increased time taken for series of recording operations including the discharge recovery processing, the reduced amount of ink for recording will raise the cost required for the recording or the running cost, and further shorten the life of the waste ink tank for receiving the discharged ink, as well as the life of the recording apparatus. The discharge recovery processing required to attain the excellent recording condition after the replacement of the recording head or ink tank is necessary to have a greater effect than when not in replacement, for which it is the common practice to repeat the discharge recovery processing in series multiple times. In such a case, if the discharge recovery processing is performed by the operator, the wasteful ink discharge amount will be possibly further increased as compared with the case where one automatic discharge recovery processing is performed.
On the other hand, in receiving the ink within the cap into the waste ink tank, there is a problem that where the ink within the cap is received after discharging the ink with suction, the unsuitable ink may be touched with the nozzles or their neighborhood, because of the preliminary discharge to be performed until the subsequent capping operation, or the movement of the ink within the cap over time.
In a conventional blade cleaner unit 49 as shown in FIG. 39, to attach it to the carriage 11 requires a presser plate 49c and two screws, in addition to a blade cleaner holder 49b, which was inconvenient because of too many parts. Also, the blade cleaner unit 49 is secured only by the snap-in action to the carriage 11, with more or less looseness contained, and particularly there is a great dispersion in the top position of blade cleaner on the blade side, which was inconvenient due to its effect on the cleaning performance. Further, Rubycerclean (Toyo Polymer Co.,Ltd.) which is useful for the wiper blade is a special and expensive material, in which if there is a great supposed number of sheets to be printed for the recording apparatus, it is necessary to provide a large volume of the wiper blade, inconveniently resulting in the higher costs.
Also, in a conventional waste ink tank, Vaporload used for the breathable film is one in which a waterproof, moisture permeable layer is coated thin over the back face of a cloth made of polyester, in which the breathable film 55c, when welded over an opening portion provided on the waste ink tank 55, is liable to wrinkles, and can not be welded singly. Hence, it is necessary to prepare other member,,and weld it with the other member sandwiched therebetween, for which a presser plate 55f is required, inconveniently resulting in too many parts.
Further, conventionally, the electrical component was disposed beneath the head recovery unit and the waste ink tank, as previously described. Therefore, if an abnormal condition, for example, "a tube 57 for feeding the waste ink to the waste ink tank is disconnected", occurred, there was a risk that the ink sucked from the head may drip to the lower electrical component. Hence, there is the necessity of providing a cover to keep the electrical component away from the ink, a part serving as the "trough" for feeding the ink to the site off the electrical component or a member for absorbing the ink, resulting in the higher costs of the apparatus itself, which was inconvenient.
The conventional waste ink seal is provided with a hole 521c for ink flow passage on the curved surface of cylindrical outer shape, and is difficult to raise the finish level of the face of a mold for molding the waste ink seal and opposed to the seal surface, which was inconvenient.
In the mold for molding the seal surface on the side of waste ink cap, it is necessary to divide the mold to mold the ink flow passage. However, since the seal surface is curved, it is difficult to modify the mold and make a smooth curved face to reduce the, step of the seal surface produced by dividing the mold, which was inconvenient.
In an ink jet printer having the nozzle protection mechanism as previously described, the capping position may be shifted due to the dimensional variations caused by the printer temperature variations for the components of the recovery unit such as a nozzle protection mechanism, a printer chassis to which the recovery unit and a carriage home sensor are secured, a sensor light shielding plate for a carriage home sensor formed integrally with the carriage, or the sensitivity variations of the carriage home sensor caused by the printer temperature variations, resulting in inaccurate capping, in some cases causing a problem of clogging the nozzles.
When the excitation phase of the carriage motor at the carriage home position calculated and the actual stop phase are different, the driving amount at the first excitation upon redriving the carriage is one step or more, whereby there is a problem that if this step is greater, the impact noise may be produced in redriving.
In the recording apparatuses with a variety of recording methods, including the ink jet printer, at the power-on and the reset, an initial state setting signal (hereinafter referred to as an initial signal) is sent from the host computer or host processor, (hereinafter referred to as a host) and received by the recording apparatus, whereupon the initial setting (hereinafter referred to as an initial operation) is effected. One of the initial operations is an initial operation of the motor associated with the recording apparatus.
FIG. 44 shows a time chart regarding the initial operation of the motor. Note that for the explanation, the motor is a four phase pulse motor of the unipolar system wherein one directional current is only flowed through the coil, and the control system is an I-phase excitation wherein the current always in only one phase is flowed, wherein the motor is rotated only in a fixed direction at the initial operation. Also, the excitation (hereinafter referred to as conduction) initiation phase at the initial operation of the motor is necessarily initiated from the same phase (A phase in the figure), wherein the operation referred to as a hold as described blow is included at the first excitation.
Generally, in driving the motor, the motor which is normally in the non-excitation state (state a-0) is subjected to excitation to gradually increase the speed or a so-called acceleration (state a-2), until a predetermined speed is reached, and thereafter driven at a constant rate (state a-3). However, the motor may be rotated apart from the actual control operation, for example, so as to enable the carrier to be moved by the user or other external means. In this case, the rotor stop position of the motor is not fixed, and even if the recording is actually started, with the motor excited, a so-called step-out in which the rotor can not follow the excitation may occur, when the excitation phase and the phase where the rotor is actually stopped are matched. Accordingly, normally, the first excitation time is lengthened, and after the rotor is matched with the excitation phase, the excitation phase is switched so that the motor is controlled to be driven for rotation. This lengthening of the first excitation time is called a hold and its time called a hold time.
As shown in FIG. 44, after the recording apparatus receives an initial signal, the motor is subjected to the hold operation (state a-1), the acceleration (state a-2), the fixed speed driving (state a-3), thereafter the deceleration (state a-4), and the completion of the initial operation (state a-5), previously described. As shown in this figure, the initial conduction to each predetermined phase of the motor is referred to as a motor initial.
By the way, .DELTA.t.sub.1 in the figure is a time from the start of initial operation for the recording apparatus to the start of actual motor initial, this time being smaller than the times .DELTA.t.sub.2 and .DELTA.t.sub.3 for the states a-1 and a-3. Hereinafter, .DELTA.t.sub.1 =5 .mu.s, .DELTA.t.sub.2 =10 ms, and .DELTA.t.sub.3 =1ms are supposed for the explanation.
FIG. 45 shows a time chart representing the initial operation of the motor wherein the initial signal is sent consecutively every 9.005 ms, due to host malfunction, and is received by the recording apparatus. As shown in FIG. 45, the motor is repeatedly transferred to the state a-1, and excited at a ratio of 9000 to 5 in the A phase. That is, this state is substantially equivalent to the continuously excited state or so-called a motor lock state. If this state is continued, the internal temperature of the motor will rise, possibly leading to a fuming or firing. This is a phenomenon which is not limitative to the state a-1, but likewise can occur in the states of a-2to a-4, and which will occur even if the initial signal is not necessarily received at an equal interval.